The present invention is directed to an antenna (spatial) processing useful in wireless communication applications, such as short-range wireless applications.
Composite Beamforming (CBF) is an antenna processing technique in which a first communication device, having a plurality of antennas, weights a signal to be transmitted by its antennas to a second communication device also having a plurality of antennas. Similarly, the second communication device weights and combines the received signals received by its antennas. A multiple-input/multiple-output (MIMO) optimized communication system is defined by CBF. The transmit weights and receive weights are determined to optimize the link margin between the devices, thereby significantly extending the range of communication between the two communication devices. Techniques related to composite beamforming are the subject matter of above-identified commonly assigned co-pending application.
There is room for still further enhancing this CBF technique to optimize cost and implementation issues at the expense of only slight degradation in performance. Such a solution is extremely valuable in manufacturing a cost-effective integrated circuit solution.
An equal gain composite beamforming technique is provided that adds the constraint that the power of the signal output by of the plurality of transmit antennas is the same, and is equal to the total power of the transmit signal divided by the number N of transmit antennas from which the signal is to be transmitted. This reduces output power requirements at each antenna. By reducing output power requirements for each power amplifier, the silicon area of the power amplifiers are reduced by as much as N times (where N is the number of transmit antennas) relative to non-equal gain CBF. Many implementation advantages are achieved by equal gain CBF, including savings in silicon, power requirements, etc.
The above and other objects and advantages will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.